1. Field of the Invention
The present invention concerns a novel member of the tumor necrosis factor (TNF) family of cytokines. In particular, isolated nucleic acid molecules are provided encoding the endokine alpha protein. Endokine alpha polypeptides are also provided, as are vectors, host cells and recombinant methods for producing the same. Also provided are diagnostic and therapeutic methods concerning TNF family-related disorders.
2. Related Art
The cytokine known as tumor necrosis factor-xcex1 (TNFxcex1; also termed cachectin) is a protein secreted primarily by monocytes and macrophages in response to endotoxin or other stimuli as a soluble homotrimer of 17 kD protein subunits (Smith, R. A. et al., J. Biol. Chem. 262:6951-6954 (1987)). A membrane-bound 26 kD precursor form of TNF has also been described (Kriegler, M. et al., Cell 53:45-53 (1988)).
Accumulating evidence indicates that TNF is a regulatory cytokine with pleiotropic biological activities. These activities include: inhibition of lipoprotein lipase synthesis (xe2x80x9ccachectinxe2x80x9d activity) (Beutler, B. et al., Nature 316:552 (1985)), activation of polymorphonuclear leukocytes (Klebanoff, S. J. et al., J. Immunol. 136:4220 (1986); Perussia, B., et al., J. Immunol. 138:765 (1987)), inhibition of cell growth or stimulation of cell growth (Vilcek, J. et al., J. Exp. Med. 163:632 (1986); Sugarman, B. J. et al., Science 230:943 (1985); Lachman, L. B. et al., J. Immunol. 138:2913 (1987)), cytotoxic action on certain transformed cell types (Lachman, L. B. et al., supra; Darzynkiewicz, Z. et al., Canc. Res. 44:83 (1984)), antiviral activity (Kohase, M. et al., Cell 45:659 (1986); Wong, G. H. W. et al., Nature 323:819 (1986)), stimulation of bone resorption (Bertolini, D. R. et al., Nature 319:516 (1986); Saklatvala, J., Nature 322:547 (1986)), stimulation of collagenase and prostaglandin E2 production (Dayer, J.-M. et al., J. Exp. Med. 162:2163 (1985)); and immunoregulatory actions, including activation of T cells (Yokota, S. et al., J. Immunol. 140:531 (1988)), B cells (Kehrl, J. H. et al., J. Exp. Med. 166:786 (1987)), monocytes (Philip, R. et al., Nature 323:86 (1986)), thymocytes (Ranges, G. E. et al., J. Exp. Med. 167:1472 (1988)), and stimulation of the cell-surface expression of major histocompatibility complex (MHC) class I and class II molecules (Collins, T. et al., Proc. Natl. Acad. Sci. USA 83:446 (1986); Pujol-Borrel, R. et al., Nature 326:304 (1987)).
TNF is noted for its pro-inflammatory actions which result in tissue injury, such as induction of procoagulant activity on vascular endothelial cells (Pober, J. S. et al., J. Immunol. 136:1680 (1986)), increased adherence of neutrophils and lymphocytes (Pober, J. S. etal., J. Immunol. 138:3319 (1987)), and stimulation of the release of platelet activating factor from macrophages, neutrophils and vascular endothelial cells (Camussi, G. et al., J. Exp. Med. 166:1390 (1987)).
Recent evidence implicates TNF in the pathogenesis of many infections (Cerami, A. et al., Immunol. Today 9:28 (1988)), immune disorders, neoplastic pathology, e.g., in cachexia accompanying some malignancies (Oliff, A. et al., Cell 50:555 (1987)), and in autoimmune pathologies and graft-versus host pathology (Piguet, P.-F. et al., J. Exp. Med. 166:1280 (1987)). The association of TNF with cancer and infectious pathologies is often related to the host""s catabolic state. A major problem in cancer patients is weight loss, usually associated with anorexia. The extensive wasting which results is known as xe2x80x9ccachexiaxe2x80x9d (Kern, K. A. et al. J. Parent. Enter. Nutr. 12:286-298 (1988)). Cachexia includes progressive weight loss, anorexia, and persistent erosion of body mass in response to a malignant growth. The cachectic state is thus associated with significant morbidity and is responsible for the majority of cancer mortality. A number of studies have suggested that TNF is an important mediator of the cachexia in cancer, infectious pathology, and in other catabolic states.
TNF is thought to play a central role in the pathophysiological consequences of Gram-negative sepsis and endotoxic shock (Michie, H. R. et al., Br. J. Surg. 76:670-671 (1989); Debets, J. M. H. et al., Second Vienna Shock Forum, p.463-466 (1989); Simpson, S. Q. et al., Crit. Care Clin. 5:27-47 (1989)), including fever, malaise, anorexia, and cachexia. Endotoxin is a potent monocyte/macrophage activator which stimulates production and secretion of TNF (Kombluth, S. K. et al., J. Immunol. 137:2585-2591 (1986)) and other cytokines. Because TNF could mimic many biological effects of endotoxin, it was concluded to be a central mediator responsible for the clinical manifestations of endotoxin-related illness. TNF and other monocyte-derived cytokines mediate the metabolic and neurohormonal responses to endotoxin (Michie, H. R. et al., N. Eng. J. Med. 318:1481-1486 (1988)). Endotoxin administration to human volunteers produces acute illness with flu-like symptoms including fever, tachycardia, increased metabolic rate and stress hormone release (Revhaug, A. et al., Arch. Surg. 123:162-170 (1988)). Elevated levels of circulating TNF have also been found in patients suffering from Gram-negative sepsis (Waage, A. et al., Lancet 1:355-357 (1987); Hammerle, A. F. et al., Second Vienna Shock Forum p. 715-718 (1989); Debets, J. M. H. et al., Crit. Care Med. 17:489-497 (1989); Calandra, T. et al., J. Infec. Dis. 161:982-987 (1990)).
Passive immunotherapy directed at neutralizing TNF may have a beneficial effect in Gram-negative sepsis and endotoxemia, based on the increased TNF production and elevated TNF levels in these pathology states, as discussed above.
Antibodies to a xe2x80x9cmodulatorxe2x80x9d material which was characterized as cachectin (later found to be identical to TNF) were disclosed by Cerami et al. (EPO Patent Publication 0,212,489, Mar. 4, 1987). Such antibodies were said to be useful in diagnostic immunoassays and in therapy of shock in bacterial infections. Rubin et al. (EPO Patent Publication 0,218,868, Apr. 22, 1987) disclosed monoclonal antibodies to human TNF, the hybridomas secreting such antibodies, methods of producing such antibodies, and the use of such antibodies in immunoassay of TNF. Yone et al. (EPO Patent Publication 0,288,088, Oct. 26, 1988) disclosed anti-TNF antibodies, including mAbs, and their utility in immunoassay diagnosis of pathologies, in particular Kawasaki""s pathology and bacterial infection. The body fluids of patients with Kawasaki""s pathology (infantile acute febrile mucocutaneous lymph node syndrome; Kawasaki, T., Allergy 16:178 (1967); Kawasaki, T., Shonica (Pediatrics) 26:935 (1985)) were said to contain elevated TNF levels which were related to progress of the pathology (Yone et al., supra).
Other investigators have described mAbs specific for recombinant human TNF which had neutralizing activity in vitro (Liang, C-M. et al. Biochem. Biophys. Res. Comm. 137:847-854 (1986); Meager, A. et al., Hybridoma 6:305-311 (1987); Fendly et al., Hybridoma 6:359-369 (1987); Bringman, T. S. et al., Hybridoma 6:489-507 (1987); Hirai, M. et al., J. Immunol. Meth. 96:57-62 (1987); Moller, A. et al. (Cytokine 2:162-169 (1990)). Some of these mAbs were used to map epitopes of human TNF and develop enzyme immunoassays (Fendly et al., supra; Hirai et al., supra; Moller et al., supra) and to assist in the purification of recombinant TNF (Bringman et al., supra). However, these studies do not provide a basis for producing TNF neutralizing antibodies that can be used for in vivo diagnostic or therapeutic uses in humans, due to immunogenicity, lack of specificity and/or pharmaceutical suitability.
Neutralizing antisera or mAbs to TNF have been shown in mammals other than man to abrogate adverse physiological changes and prevent death after lethal challenge in experimental endotoxemia and bacteremia. This effect has been demonstrated, e.g., in rodent lethality assays and in primate pathology model systems (Mathison, J. C. et al., J. Clin. Invest. 81:1925-1937 (1988); Beutler, B. et al., Science 229:869-871 (1985); Tracey, K. J. et al., Nature 330:662-664 (1987); Shimamoto, Y. et al., Immunol. Lett. 17:311-318 (1988); Silva, A. T. et al., J. Infect. Dis. 162:421-427 (1990); Opal, S. M. et al., J. Infect. Dis. 161:1148-1152 (1990); Hinshaw, L. B. et al., Circ. Shock 30:279-292 (1990)).
To date, experience with anti-TNF mAb therapy in humans has been limited but shows beneficial therapeutic results, e.g., in arthritis and sepsis. See, e.g., Elliott, M. J. et al., Baillieres Clin. Rheumatol. 9:633-52 (1995); Feldmann M, et al., Ann. N.Y. Acad. Sci. USA 766:272-8 (1995); van der Poll, T. et al., Shock 3:1-12 (1995); Wherry et al., Crit. Care. Med. 21:S436-40 (1993); Tracey K. J., et al., Crit. Care Med. 21:S415-22 (1993).
Sequence analysis of cytokine receptors has defined several subfamilies of membrane proteins (1) the Ig superfamily, (2) the hematopoietin (cytokine receptor superfamily and (3) the tumor necrosis factor (TNF)/nerve growth factor (NGF) receptor superfamily (for review of TNF superfamily see, Gruss and Dower, Blood 85(12):3378-3404 (1995) and Aggarwal and Natarajan, Eur. Cytokine Netw., 7(2):93-124 (1996)). The TNF/NGF receptor superfamily contains at least 10 different proteins. Gruss and Dower, supra. Ligands for these receptors have been identified and belong to at least two cytokine superfamilies. Gruss and Dower, supra.
Accordingly, there is a need to provide cytokines similar to TNF that are involved in pathological conditions. Such novel cytokines could be used to make novel antibodies or other antagonists that bind these TNF-like cytokines for therapy of TNF-like disorders.
The present invention provides isolated nucleic acid molecules comprising a polynucleotide encoding a cytokine that is similar to TNF and is believed to have similar biological effects and activities. This cytokine is named endokine alpha, and includes endokine alpha polypeptides having at least a portion of the amino acid sequence in FIGS. 1A-1B (SEQ ID NO:2) or an amino acid sequence encoded by the cDNA clone deposited as ATCC Deposit Number 97640 on Jun. 27, 1996. The nucleotide sequence, which was determined by sequencing the deposited endokine alpha cDNA clone, contains an open reading frame encoding a polypeptide of about 169 amino acid residues including an N-terminal methionine, an intracellular domain of about 17 amino acid residues, a transmembrane domain of about 26 amino acids, an extracellular domain of about 126 amino acids, and a deduced molecular weight for the complete protein of about 19 kDa.
Thus, one aspect of the invention provides an isolated nucleic acid molecule comprising apolynucleotidehaving anucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding the endokine alpha polypeptide having the complete amino acid sequence in SEQ ID NO:2; (b) a nucleotide sequence encoding the endokine alpha polypeptide having the complete amino acid sequence in SEQ ID NO:2 but minus the N-terminal methionine residue; (c) a nucleotide sequence encoding the endokine alpha polypeptide having the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97640; and (d) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b) or (c) above.
Further embodiments of the invention include isolated nucleic acid molecules that comprise or, alternatively, consist of, a polynucleotide having a nucleotide sequence at least 80%, 85%, 90%, 92%, or 95% identical, and more preferably at least 96%, 97%, 98% or 99% identical, to any of the nucleotide sequences in (a), (b), (c), or (d), above, or a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide in (a), (b), (c), or (d), above. This polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues. An additional nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a endokine alpha polypeptide having an amino acid sequence in (a), (b), (c), or (d), above.
The invention is further directed to nucleic acid fragments of the nucleic acid molecules described herein. Preferred nucleic acid fragments include nucleic acid molecules which encode: a polypeptide comprising the endokine alpha intracellular domain (amino acid residues from about 1 to about 17 in FIGS. 1A-1B (SEQ ID NO:2)); a polypeptide comprising the endokine alpha transmembrane domain (amino acid residues from about 18 to about 43 in FIGS. 1A-1B (SEQ ID NO:2)); and a polypeptide comprising the endokine alpha extracellular domain (amino acid residues from about 44 to about 169 in FIGS. 1A-1B (SEQ ID NO:2)).
The present invention also relates to recombinant vectors, which include the isolated nucleic acid molecules of the present invention, and to host cells containing the recombinant vectors, as well as to methods of making such vectors and host cells and for using them for production of endokine alpha polypeptides or peptides by recombinant techniques.
The invention further provides an isolated endokine alpha polypeptide having an amino acid sequence selected from the group consisting of: (a) the complete 169 amino acid sequence in SEQ ID NO:2; (b) the complete 169 amino acid sequence in SEQ ID NO:2 but minus the N-terminal methionine residue; (c) the complete amino acid sequence encoded by the cDNA clone contained in ATCC Deposit No. 97640; and (d) the amino acid sequence of an epitope-bearing portion of any one of the polypeptides of (a), (b), or (c). The polypeptides of the present invention also include polypeptides having an amino acid sequence at least 80%, 85%, 90%, 92%, or 95% identical, more preferably at least 96%, 97%, 98% or 99% identical to those above.
Peptides or polypeptides having the amino acid sequence of an epitope-bearing portion of a endokine alpha polypeptide of the invention include portions of such polypeptides with at least six or seven, preferably at least nine, and more preferably at least about 30 amino acids to about 50 amino acids, although epitope-bearing polypeptides of any length up to and including the entire amino acid sequence of a polypeptide of the invention described above also are included in the invention.
In another embodiment, the invention provides an isolated antibody that binds specifically to an endokine alpha polypeptide having an amino acid sequence described in (a), (b), (c), or (d) above.
Preferred polypeptide fragments according to the present invention include a polypeptide comprising: the endokine alpha intracellular domain, the endokine alpha transmembrane domain, and the endokine alpha extracellular domain.
The invention further provides methods for isolating antibodies that bind specifically to an endokine alpha polypeptide having an amino acid sequence as described above. Such antibodies may be useful diagnostically or therapeutically as antagonists in the treatment of endokine alpha- and/or TNF-related disorders. The invention also provides a diagnostic method for determining the presence of a TNF-related disorder.